System for the precipitation of solid particles from gases



Aug. 6, 1935. c. c. LEVY 2,010,599

SYSTEM FOR THE PRECIPITATION OF SOLID PARTICLES FROM GASES Filed Feb. 14, 1954 INVENTOR (J 77'! GL6 y.

Patented Aug. 6, 1935 PATENT OFFICE SYSTEM FOR THE PRECIPITATION OF SOLID PARTICLES FROM GASES Cyril (L-Levy, Pittsburgh, Pa., assignor to Westinghouse Electric & Manufacturing Company,

East Pittsburgh, Pa.,

sylvania a corporation of Penn'- Application February 14. 1934, Serial No. 711,193

9 Claims.

The invention relates generally to systems for the precipitation of solid particles from gases.

The object of the invention is to provide for maintaining substantially continuously an ionizing charge on the plates or members employed in a system for precipitating solid particles from gases.

It is also an object of the invention to provide for a time delay between the establishment of the tube heating circuits and the charging circuits of a precipitating system.

Other objects of the invention will. in part, be obvious and, in part, appear hereinafter.

The invention accordingly is disclosed in the accompanying drawing and comprises the features of construction,combination of elements I and arrangement of parts which will be exemplifled in the structure hereinafter set forth and the scope of which will be indicated in the claims.

For a fuller understanding of the objects of the invention, reference may be had to the following detailed description taken in connection with the accompanying drawing, in which:

The. figure is a diagrammatic view of a control system arranged in accordance with this invention.

Referring now to the drawing. l0 designates generally a stack or pipe through which large volumes of gases containing solid particles flow or are conveyed and from which it is desired to precipitate the solid particles. In certain industries, it has been found that valuable products are carried away in the form of solid particles suspended in smoke and fumes that rise from furnaces and escape through the stacks. In many instances, it has been found profitable to collect these solid particles by means of precipitating systems. 7

In the iron and steel industry, in the operation of blast furnaces large volumes of gases are produced that may be employed for operating internal combustion engines. The gases as they come from the furnaces are laden with. solid particles which have to be removed in order to avoid the fouling of the engines.

The present system was developed primarily to precipitate solid particles out of gases. In installations made the gases from gas furnaces have been so cleared of solid particles that they were entirely satisfactory for fuel for internal combustion engines.

As illustrated, the stack or pipe I0 is grounded at H. Wires or electrodes l2 suitable for carrying a negative ionizing charge are suspended in the stack or pipe and insulated therefrom.

These plates are connected with the charging system as shown at l3.

The charging current may be drawn from any suitable source of supply and in this instance a transmission system I4 for supplying single phase 5 alternating current is illustrated.

The precipitation of the solid particles from the gas is effected by imposing on the wires or electrodes 12 a negative charge which causes an ionization of the air or gas carrying the particles with the result that they are negatively charged and move to the stack or pipe l0 from which they may be collected in any well known manner not illustrated. The means employed for collecting the particles from the stack or pipe will depend on the'particular installation.

In order to supply the electrodes I2 with a negative charge some suitable means for rectifying the current drawn from the transmission system I4 is required. In this instance rectifying tubes are employed. The tubes illustrated are of the two electrode type each having a filament and plate but other types may be utilized.-

A continuous charging current may be delivered to the plates I! by employing a pair of properly disposed rectifying tubes. However if one of the tubes is burned out charging current is supplied only during one half of each cycle and the system will not'operate efiiciently. If the gases are to be utilized for operating internal combustion engines, the interruption of the precipitation process for one half of each cycle'will result in the fouling of the engines and in the case of stacks the loss of valuable products. In the presentsystem in order to maintain substantially continuously a charge on the plates or wires I2. two pairs of tubes l5 and l 6 are provided together with means for switching from one pair to the other in case of the failureof a tube.

It is well known that most rectifying tubes function more efficiently when the filaments are. heated independently of the current flowing through them. In the present system, transformers I1 and I8 are provided for heating the filaments of the pairs of tubes I 5 and I6, respectively. The transformers l1 and 18 are supplied from a single transformer or voltage regulating transformer l9 connected across the transmission system H. Transformers such as l9 are employed to maintain the voltage constant.' This type of transformer is well known in the art and will not be described in detail.

The current for charging the plates or wires l2 is drawn from the transmission system H through a step-up transformer 20. As illustrated.

v the electrodes l2 and ground.

a voltage regulator 2| is interposed between the transformer 20 and the transmission system H for controlling the voltage impressed on the tubes.

It often happens in the operation of a precipitating system that a short circuit occurs bet een In such cases, excessively heavy currents may be drawn from the transformer 20. In order to restrict the flow of current, a reactor 22 is provided. Any suitable type 'of switch 23 may be employe for connecting either pair of tubes l5. or l8 across the secondary of the transformer 20 and for switching from one pair of tubes .to' the other. In the system illustrated, the switch 23 employed comprises a plurality of contact members pivotally mounted on an actuating bar 24 and insulated from one another by the insulating segments 25'. Three of the contact members of the switch 23 are employed for controlling the flow of charging current from the transformer 20 through the pairs of tubes 45 and Hi to the plates while the fourth disposed at the left end of the bar 24 is provided for making and breaking control cir- 'cuits. The contact members will be identified and trolled latch 26.

A coil spring 21 disposed at the end of the bar 24 is compressed when the switch is actuated to the left. The spring 21 is so selected that when the latch 26 is released, it will project the switch 23 to the right with suflicient force to oscillate the contact members to the right toengage another set of stationary contact members. When the switch is actuated to the right, it is engaged by a latch 28 which is disposed to be manually operated.

A control system is provided for operating the switches provided for connecting the pairs of tubes l5 and I6 across their supply transformers and for switching from one pair of tubes to another upon the failure of a tube. These switches will be referred to hereinafter in connection with the description of the functioning of'the system. The current for operating the control system is supplied from the transmission system l4 through the transformer 29. V

In order to start the systemfunctioning, the switch 23 is manually projected to the left operating the pivotally mounted contact members to cooperate in the establishment of a plurality of circuits that will be traced hereinafter. When the switch 23 stands closed the start switch 30 is closed establishing an actuating circuit for the switch 3|. The switch actuating circuit extends from the energized transformer 25 through conductors 32 and 33, contact member 34 carried by the switch 23, conductor 35, switch 3.0, the actuating coil of switch 3|, conductor 36 and back to the otherside of the transformer 29.

When the switch 3| is closed, the transformer is connected across the transformer- IS, the

circuit extending from one side of the transformer l9 through conductors 3i? and 38, the middle contact member of switch 3|, the primary winding of transformer conductor 39. the lower contact member of switch 3| and conductor 40 to the other side of the transformer I9.

As shown, the filaments of the pair of rectifying tubes l5 are connected across the secondary coils of the transformer I! from which they are supplied with heating current. The voltage supplied to the filaments of the rectifying tube I5 by the transformer I! is not high enough to cause a fiow of current to the electrodes |2 and only produces a space charge.

As illustrated, a coil 4| is disposed to be energized when current flows in the conductor 3?. This current coil 4| is connected across the actuating coil of the relay 42. Therefore, when 'switch3l is actuated to its closed position, current is supplied from one terminal of the current coil 4| through conductor 43, the actuating coil of relay 42 and conductor 44 back to the other terminal of the coil 4|.

- Upon the closure'of relay 42, an actuating circuit for the switch 45 is established. Relay 45 is provided for controlling the operation of the electromagnetically operated latch 26. The actuating circuit for the relay 45 extends from the energized conductor32- through conductors 46 and 41, the upper contact member on switch 1 3|, conductor 48, the contact member of relay 42,

conductor 49, the actuating coil of switch 45 and conductor 50 back to the other terminal of transformer 29.

A relay 5| is provided for connecting the voltage regulator 2| across the transmission system |4. As soon as the voltage. regulator 2| is connected across the transmission system, the transformer 20 is energized and a charge may be imposed on the electrodes or wires I2. However, for successful operation, it is desired that the filaments of the pair of tubes |5 be heated before the high voltage from the transformer 20 is imposed on them. 1 In order to provide for the proper delay between the establishment of the heating and charging circuits a time element relay 52 is disposed to control the actuating circuit of the switch 5|. 1

' When the switch 3| is closed, an actuating circuit for the relay 52 is established but the actuating circuit for the relay 5| is not established for a predetermined time thereafter. The actuating circuit for the relay 52 extends from the energized conductor 41 through a contact mem-' her on the switch 3|, conductors 53 and 54, the actuating coil of the time element relay 52, conductor 55, an interlock on the relay 5| and conductor 56 to conductor 50.

The actuating circuit of relay 5|, in addition to being controlled by the relay 52, is dependent upon the position of the interlock provided on relay 45. When the relays 52 and 45 are closed, a circuit is established which extends from the energized conductor 53 through conductor 51, the contact members of relay 52, conductor 58, the actuating coil of relay 5|, the interlock carried by relay 45 to the conductor 50. The relay 5| is closed connecting the voltage regulator 2| across the transmission system l4. An interlock provided on the relay 5| establishes a holding circuit which may be traced from the energized conductor 53 through conductor 59, the lowermost contact member on the relay 5|, the actuating coil of relay 5| and the interlock on relay 45 to the conductor 50. When the relay 5| is actuated to its closed position, the actuating circuit for the relay 52 is interrupted by the opening of the in.interlock provided on the relay 5|. Since the voltage regulator 2| is adjustable any predetermined voltage may be impressed across the primary coil of the transformer 20.

As-shown, the secondary coils of the transformer 20 are grounded at 60. The high voltage circuit for the tubes may be traced from the secondary coils of the transformer through the contact members BI and 62, the parallel connected conductors 63 and GI to the secondary coils of the transformer I1 and the filaments of the tubes connected in parallel circuit relation to the common conductor 65, the contact member 66 on the switch 23 and conductor 61 to the electrodes or wires l2 in the stack or pipe H). In this manner, a negative voltage may be impressed upon the wires or electrodes l2. The air or gas is ionized and the solid particles carried by the gas flowing in the pipe or stack receive a negative charge from the ionized air or gas which carries them to the positively. charged surface of the stack or pipe to.

Assuming now that one of the tubes i5 is burned out or hasv become non-conducting for some other reason then the current flowing in the transformer I! will suddenly decrease. A corresponding decrease in current in the coil 4| results and the current relay 62 is deenergized and the actuating circuit of the relay is interrupted. Upon the interruption of the actuating circuit of the coil 45. an actuating circuit is established for operating the electromagnetically controlled latch 26. This circuit may be traced from the energized conductor 53 through the actuating coil of the latch 26, conductor 68. and the contact member of relay 45 to the conductor 50.

The latch 26 is rotated clockwise releasing the switch 23. The spring 21 which was energized through the manual operation of the switch 23 projects the switch to the right. When the contact member 34 of the switch 33 is actuated to the right. an actuating circuit for the relay 69 is esablished which may be traced from contact member 34 through conductor 10, the re-set switch H. conductor 12. the actuating coil of relay 69 and conductors 36 and to the transformer 29. When the switch 69 is closed. the transformer i8 is connected across the transformer Ill.

. been traced hereinbefore and it is believed unnecessary to retrace them. A high voltage is impressed on the pair of 7 tubes IS a short time after the establishment of the heating circuit.

The high voltage parallel-series circuit through which the ionizing charge is imposed on the electrodes or wires l2 extends from the secondary of the transformer 20 through contact members BI and 62, conductors l6 and 11 connected to secondaries of the transformer IS, the filaments and plates of the tubes IE to the common conductor l8 and contact member 66 of switch 23 to the common conductor 61. Again a negative voltage is impressed on the electrodes l2.

In this manner, provision is made for imposing substantially continuously an ionizing voltage on. the plates I2. The system as described.

upon the failure of one tube, functions to cut one pair of tubes out of the charging circuit and connect another pair of tubes into the charging circuit. The time interval between the establishment of the tube heating circuits and the charging circuits resulting from the use of a time-delay relay 52 is so short that it does not effect the proper functioning of the precipitating system.

When the switch 23 is actuated to the right by the spring 21, it is engaged by a latch 28 and retained in its contact making position.

A lamp 19 is connected in series circuit relation with switch member 34 and is connected across transformer 29 when the switch 23 is actu- 'ated to the right and the operator is warned that a tube has failed. It is his duty then to immediately replace the burned out tube and to re-set the circuit. Upon the replacement of the tube. the operator presses the re-set switchfil. interrupting the circuits of the relays. releasing the latch 28 and projects the switch 23 to the left. The circuits described hereinabove are then established closing the start switch 30.

I claim as my invention:

1. In a system for the precipitation of solid particles from a gas. in combination. means for carrying an electrical charge capable of ionizing the particles, a source of power for imposing a charge on the ionizing means, a plurality of rectifying units disposed to be connected successively between the source of power and the ionizing means to provide a charging circuit, means responsive to the failure of one rectifying unit for connecting another rectifying unit into the circuit. means disposed for manual operation cooperative to interrupt the circuit through one rectifying unit and establish it through another and means for checking the flow of current from the source of power to the tubes upon a change in the electrical conditions.

2. In a system for the precipitation of solid particles. in combination. means for carrying an electrical charge capable of ionizing the particles,

a source of power for imposing a charge on the ionizing means, a plurality of current rectifying tubes each having a plate and filament disposed to be connected successively, between the source of power and the charge carrying means to provide a charging circuit, means for supplying current from the source of power to heat the filaments of the tubes to facilitate the charging operation of current in the charging circuit. and

means responsive to the failure of a tube to in- 5 terrupt both the charging and heating circuits and re-establish them in a predetermined order through another tube. v

3. In a system for the precipitation of solid particles from a gaseous atmosphere, in comb'ination. means for carrying a charge capable of.

ionizing the particles in the gaseous atmosphere, a source of power for imposing a charge on the ionizing means. a plurality of rectifying tubes having filaments disposed to be connected successively between the source of power and the charge carrying means to provide a charging circuit, a circuit for heating the filament of each tube, means for interrupting the charging and heating circuits upon the failure of one tube and establishing them through another tube and means cooperative to effect a time delay between the establishment of the heating and charging circuits.

4. In a system for the precipitation of solid particles from a gaseous atmosphere, in combination, means for carrying an electrical charge capable of ionizing the particles, a source of power for imposing a charge on the ionizing means, a plurality of current rectifying tubes, means a current rectifying tube between the source of power and the charge carrying means to provide a charging circuit, means responsive to the failure of the current rectifying tube and for interrupting the charging circuit through one tube and establishing it through another and means for indicating the transfer from one tube to another has been effected.

5. In a system for the precipitation of solid particles from a gaseous atmosphere, in combination, means for carrying an electrical charge capable of ionizing the particles, a source of power for imposing a charge on the ionizing means, a plurality of rectifying tubes disposed to be connected between the source of power and the charge carrying means, each of said tubes being provided with a filament, means for connecting a current rectifying tube between the source of power and the charge carrying means to provide a charging circuit, means for connecting the filament of a tube to the source of power to establish a heating circuit, means disposed for manual operation for effecting the actuation of means provided for establishing the charging and heating circuit, and means responsiveto the failure of a tube for interrupting the charging and heating circuits of one tube and establishing charging and heating circuits for another tube to provide a substantially continuous charging operation.

6. In a system for the precipitation of solid particles from a gaseous atmosphere, in combination, means for carrying an electrical charge capable of ionizing the particles, a source of power for imposing a charge on the ionizing means, a plurality of rectifying tubes disposed to be connected between the source of power and the charge carrying means, each of said tubes being provided with a filament, means for conmeeting a current rectifying tube between the source of power and the charge carrying means to provide a charging circuit, means for connecting the filament of a tube to the source of power to establish a heating circuit, means disposed for manual operation for effecting the actuation of means provided for establishing the charging and heating circuit, means responsive to the failure of a tube for interrupting the charging and heating circuits of one tube and establishing charging and heating circuits for another tube to provide a substantially continuous charging operation and means cooperative to effect a time delay between the establishment of the heating disposed for manual operation for connecting circuit for each tube and the charging circuits.

7. In a system for the precipitation of solid particles from a gaseous medium, in combination, means for carrying an electrical charge capable of ionizing the particles, a source of power, a transformer connected across the source of power, a plurality of current rectifying tubes disposed to be connected across the transformer and to the ionizing means to provide a charging circuit, a reactor connected in series circuit relation with the transformer to limit the current flow upon the failure of the tube and means responsive to the failure of the tube for interrupting the charging circuit from one tube and establishing it from another tube.

8. In a system for the precipitation of solid particles from a gaseous medium, in combination, means for carrying an electrical charge capable of ionizing the particles, a source of-power, a plurality of current rectifying tubes disposed to be connected between the source of power and the charge carrying means to provide a charging circuit, atransformer connected to the source of power, means disposed for manual op eration for connecting a tube across the transformer to the charge carrying means, and means responsive to the failure of a tube for interrupting a charging current from one tube and establishing it through another to maintain substantially continuously a charging circuit and a reactor connected between the transformer and source of power cooperative to check the flow of current.

9. In a system for the precipitation of solid particles from a gaseous medium, in combination, means for carrying an electrical charge capable of ionizing the particles, a source'of power, a plurality of current rectifying tubes disposed to be connected between the source of power and the charge carrying means to provide a charging circuit, a transformer connected to the source of power, means disposed for manual operation for connecting a tube across the transformer and to the charge carrying means, means responsive to the failure of a tube for interrupting a charging current from one tube, and establishing it through another to maintain substantially continuously a charging circuit, a tube heating circuit and means cooperative for transferring heating circuits from one tube to another as the charging circuit is transferred and means for causing a time delay between the establishment of the heating circuit and the charging circuit.

CYRIL C. LEVY. 

